Oxazole and oxadiazole benzoic acid derivatives as herbicides

ABSTRACT

Certain 2-(1,3,4-oxadiazole-2-yl) benzoic acids and salts and esters thereof, as well as certain 2-(2-oxazolyl) benzoic acids, salts and esters, having the formula:   WHERE X is nitrogen or C-R&#39;&#39;&#39;&#39; (R&#39;&#39;&#39;&#39; being hydrogen or methyl), R is phenyl or various substituents, and R&#39;&#39; and the Y&#39;&#39;s are hydrogen or various substituents (e.g., 2-(5-phenyl-1,3,4oxadiazole-2-yl) benzoic acid),are effective preemergence or postemergence herbicides, on various crops. The chemicals act selectively and are useful against purple nutsedge and in cranberry. Oxadiazoles of the invention may be made by reacting a benzhydrazide with phthalic anhydride to form a hydrazide which is cyclized by removal of the elements of water, using as a catalyst fuming sulfuric acid or dimethylformamide-sulfur trioxide complex.

Brouwer et al.

May 6, 1975 UN OXAZOLE AND OXADIAZOLE BENZOIC ACID DERIVATIVES AS HERBICIDES [75] Inventors: Walter G. Brouwer, Gulph. Ontario;

Edwin J. MaePherson, Waterloo. Ontario. both of Canada; Ronald B. Ames, Naugatuek. COm'L', Robert W. Neidermyer, Cheshire. N.H.

[73] Assignees: Uniroyal, lnc., New York. N.r'.;

Uniroyal Ltd., Montreal, Canada [22] Filed: Aug. 9, l97l 121] App]. No.: [70,263

[52] US. Cl. 260/307 G; 71/90; 7l/92; 260/2948 D; 260/295 R; 260/307 R; 260/308 D; 260/326 N; 260/518 R; 260/5l8 A; 260/558 H; 260/559 H [51] Int. Cl C07d 85/54 [58] Field of Search 260/307 G 294.8 D. 295 R [56] References Cited UNITED STATES PATENTS 2165.304 Ill/I956 Siegrist ct al. 260/240 1481949 l2/l969 Lynch et all 260/307 OTHER PUBLICATIONS Behr Heterocyclic Compounds." Vol. l7. lnterscience Publishers (i962) pp 265268.

Huisgen et al. (1) CA. 55, 2626h( 1960). Abstract of Her 93,2106 l960).

Huisgen et al. ([1) CA 63, l628lhtl965). Abstract of Ber. 98 2966. (i965).

Grekov et al, (1) CA. 54. 9899b (1959) Abstract of Zhuri Obschehei Khim., 29. 2027 (I959).

Grekov et al, (ll) CA. 55. 21 103g [960) Abstract of Zhur Obschehei Khim.. 30. 3802 (1960].

Primary E.t'ami!ierDonuld G. Duus Assistant Eraminer-Raymond V. Rush ,ltmrney. Agent. or Firm-James J, Long [57 I ABSTRACT Certain 2-(l.3.4 oxadiazole-2yl) hcnzoic acids and salts and esters thereof, as well as certain 2-(2- oxazolyl) benzoic acids. salts and esters. having the formula:

where X is nitrogen or CR" tR" being hydrogen or methyl), R is phenyl or various substituents. and R and the Ys are hydrogen or various substituents [e g.. 2-(S-phenyIAlQA-oitadiazole2-yll benzoic aeidLure effective preemdi-genee or postemergence herbicides. on various crops. The chemicals act selectively and are uscful ligainst purple nutsedge and in cranberry. Oxadiazolfis of the invention may he made by reacting a henzhyatirazide with pE thalic anhydride to form a hy drazid'e ivhich is cycliz d by removal of the elements of water. using as a catalyst fuming sulfuric acid or dimcthylformamide-sulfur trioxide complex.

- 6 Claims, N0 Drawings l 2 ()XAZULE AND ()XADIAZOLE BENZUK AF") Z-(Z-oxazolyl) bcnzoic acids. salts and esters. are also DERIVATIVES AS HERBICIDES effective herbicides.

In more detail. herbicidal chemicals of the invention This invention relates to certain osadiazoles as new may be represented by the formula chemicals and methods of making same. and it also re- 5 lates to the use of such osadiamles. and certain o\a- X- loles. as herbicides. /l|\ I 000R Weeds are undersirable plants because they compete R Y vvith crops for available space. light. nutrients and moisture. causing reductions in crop yield. because to Y 2 they lower crop quality. harbor diseases and insect 3 pests of plants and adversely affect the usefulness of non-crop land. The cost of controlling the needs has where X. R. and the Y's are as previously defined and been reduced by the use of herbicides. ln accordance R is hydrogen or a salt-forming or ester-forming moivvith the present invention it has now been found that 5 ety. When R' is hydrogen this formula of course repreccrtain derivatives ofZ-t l.3.4 oxadiazole-2-yl) benzoic sents the benzoic acids themselves. In the salts. R is acid and 2-! 2-oxa7olyl) benzoic acid. herein referred to typically an alkali metal (preferably sodium or potasas oxadiazoles and oxa7oles. respectively. are effective sium although lithium or other metal may also be used as herbicides. as the salt-forming moiety. including polyvalent metals The oxazoles and oxadiazoles found to be active as such as copper. zinc. calcium. barium. magnesium iron herbicides in accordance with the invention are benand the like). ammonium. alkylammonium htoing up ltllC acids (or salts or esters thereof) having the follovvto II carbon atoms (cg. methylammonium. ethyl-aming structure: monium. diethylammonium. hesylammonium. dodecylammonium). alkanolammonium having up to [2 carbon atoms (cg. ethanolammonium. diethanolarw X C00 monium. hesanolammonium. dodecanolammonium Jl l choline. and the like. lit the esters. R is commonly rep R 0 Y1 resented by aliphatic or cycloaliphatic hydrocarhyl Y Y moieties having up to II carbon atoms. notably alkyl 2 (cg. methyl. ethyl. n-propyl. iso-propyl. n-butyl. lso

3 butyl. sec.-butyl. tert.-butyl. hevyl. iso-octyl. dodccyl I. alkcnyl leg. vinyl. allyl. methallyl. l-hcvenyl. 3 hexenyl. Z-dodecenyl. 4-dodecenyl. etc. alkynyl leg.

vvhercin: l-propynyl. Z-butynyl. 3-hesynyl. S-dodeeynyl. etc). X is nitrogen or (-R" tR" being hydrogen or 35 cycloalkyl having up to l2 carbon atoms te.g.. cyclo methyl I; propyl. cyclohexyl. cyclododecyl. etc. and the like. or R is hydrogen. lower alkyl. a heterocyclic group or by epoxyalkyl (e.g.. ZB-eposypropyl. IJ-eposybutyl. the group 3.4-epoxybutyl. IB-epoxyhesyl. 4.5epos voctyl. 2.3-

epoxydodecyl. 5,6-epoxydodecyl. etc.) In addition to Y the acids themselves IR is hydrogen) preferred bodies Y are the alkali metal salts (R' is alkali metal) and the alkyl esters (R' is alkyl). Y Y In other preferred chemicals the hemoic acid ring is 7 5 unsubstituted (that is. Y Y Y and Y are hydro 6 gen).

Also particularly advantageous in certain respects and the Y 's are the same or different and are selected are chemicals in which the S-substituent (R) on the osfrom the group consisting of hydrogen. halogen. nitro. azole or oxadiazolc ring is phenyl. that is. Y,-,. Y Y;. lovver alkyl. and lower alkoxy. W Y and Y,, are all hydrogen. or a mono-substituted phe- The chemicals in which X is nitrogen. that is. the 2- nyl. that is. all but one of Y Y Y Y. and Y, are hy- (l.3.4-oXadia2ole-2yl) henxoic acids. salts and esters. drogen (although di. tri-. tetraand pentasubstituted are believed to be new chemicals. phenyl bodies as defined herein may also be used.

One preferred sub-class of herbicidal chemicals of Examples of oxadiazoles and oxazoles useful in the the invention is that represented by the formula a control of weeds in accordance with the invention are 2-(S-phenyl-l.3.4-oxadiaZole-2-yl) benzoic acid. the x methvl ester of same. the ethvl ester of same. the butvl Y9 I l COOH ester of same the n-hexvl esfer of same the n-dodec vl 8 Q ester of same (or similar alkyl esters in which the alkyl Y group is normal or iso. primary. secondary or tertiary. 7 5 straight chain or branched). Z-l5-(1-tolyl)-l.3.4- oxadiazole-Z-yll benmic acid (also the 3-tolyl and 4- tolyl analogs of same). ethyl Z-l5-(2.3-dimethylwhere X and the Y's have the values previously stated. phenyl l .3.4-oxadiazole-2-yl| henzoate. 2-( S-methyl- Ofthcse. the new chemicals in which X is nitrogen. that M l.3.4-osadiazole-2-yl) benzoic acid. sec.-butyl Z-t S-nis. the 2-( l.3.4 ovadiazolylQ-yl) benzoic acids. salts hcxyl-l.3.4-oxadiazole-2-yl) bemoate. Z-(S-isopropyland esters constitute an important sub-class. although l.3.4 oxadiazole2-yl) bcnzoic acid. amyl 2-l5-(Z.3.4-

the chemicals in which X is (H or ('(H,-,. that is. the trimethylphenyH-l.3.4-oxadiazole-Z-yll benzoate. Z

l5-(-lchlorophenyl)-l.3.4-ox;itlta7ole-ZylI l'ienloic acid. methyl Z-l5-(2.3.4-trihromophenylH.14- oxadiazolc2yl| henzoate. 2 54 Lnitrophcnylhl 3.4- UXtltilllZtilC-2 \ll hcnzoic acid. isopropyl 2-[5-(2- chloro-3-nitro--l-methoxyphenyl l .SA-oxadiazolc- Z-yll hcni'oate. methyl Z|5%2.?-.4-trimethosyphenyl)- l.3.4 oxadia7ole lyll hen/oate. ethyl It F-cthyl l 3.4- oxadiazolei vl) henzoatc. tcrt.-hutyl 2(5phenyl2- oxazolyll henzoate. methyl Z-l5(Z-tluoro-3-anisyll-4- methyl-Z-oxazolyll henzoatc. Z-li tl-nitrophenylhl oxazolyll henzoic acid. Z-I5( 2.3.4-trichlorophcnyl)-2- oxazolyll henzoic acid. sodium Z-|5-(2.3.4-trichlorophenyl)3-oxazolyl] henzoate. n-dodecyl Z-[4-mcthyl- 5-( 3-pyridyl)Q-oxazolyll benzoate. ethyl Z-l 5 l l 3.4.5-tetrachlorophenyl l .3.4-oxadiazole2yll hcnzoate. ethyl Ll5-lZ.3.45.h-pentachlorophenyl) l.3.4-oxadiazole'2-yll henzoate. -[5-(Z.3-dihromo-4- hutoxy5-nitrophcnyll--l-mcthyl-loxazolyl|3- cthylhenmic acid. isohutyl Z-|5-phenyl-l.3.4- oxadia7ole-1yl}3.-1.5 -trichlorohenzoate. methyl 214- methy l-5-| lanisyl )Q-oxazolyl |-3-hromo6- nitrohcmoate. dodecyl 2-[4-methyl-5phenyl2- omt/olyl Itetrachlorohenzoate. potassium 2-t 5-phenyl- 2ti\t17.t l \l) hcnzoatc. ammonium 2-[5-phettyl-l.3.4-

oxadiazole-Z-yll henzoate. diethanolammonittm Z-lS (l-tvhutylphenylld.3.4-oxadiazolc-Z-yl1-4- tluorohenzoate, Z-I5-lichloro-B-pyridyll-l3.4- tndtllttltiltJ-jfl'li benzoic acid. cyclohcxyl 2'(5phenyll.3.4-o\adia7ole-Z-yll henzoate. n-hutyl Z452- tHtUUlylJ hcnloate. allyl Z-IS-t-l-nitrophenyll-l3.4- osadiazolwlyll-S-methyl henzoate. vinyl 2-(5-phenyl loutzolyl) henzoate. methallyl Z-t4-mcthyl5-phenyl l-oitazolyl) henz oate. 5-pentenyl 2-t5-phenyl-l.3.4- oxadiamle-Z-yll henzoate. Z-hexcnyl 2l5-[3-ethyl phenyll-l.3.4-oxadiazole-lyl] henzoate. 3-hutynyl Z- l5phcnyl-Z-osa7olyll--tniethoxyhenzoatc. 3-hcxynyl Z-l -i-methyl5-phenyl-Z-oxazolyl I henzoate. lpentynyl Z-lS-tlchlorophenyl|l.3.4-oxadia7ole-lylI henzoate. cyclopentyl Z-t5-phcnyl-l.3.4-oxadiazolc-lyl) henroate. cyclooctyl Z-l 4-methyl-5phenyl-Z- ostflolyl) hcnzoatc. 2.3-epoxypropyl Z-(S-phenyll .3.-l o\adiazolc-Z-yl) henzoate. ferric tril Z-t fi-phenyll.3.toxadiazole-Lyll henzoate manganese dilZ(i-phenyl-loxazolyl) henzoatc]. 5-iodo-Z-(5- phenyl l .3.4-oxadia7oleQ-yll henzoic acid. 3.5-diiodo- I-(S-phenyl-l.3.4-oxadia7ole-Z-yll henzoic acid. (1' nitro-Z( S-phcnyld.3.4-osadiazoleQ-yll henzoic acid. ZtS-phenyI-I.3.4-oxadiazole-2-yll3.5.6- trimetho tyhcnzoic acid. 3-chloro-2-tS-phenyl-l3.4- oxadiazolc-Z-yll henzoic acid. Z-l5-phcnyl-l.3.4- o. .atiia2ole3 \lt litvtritttcthyl hcnzoic acid. 1(5- phcnyl-l.3.4-osadia7ole-2-yll3.-l.5.htctrachlorohcmoic acid. 1-11 5 pheny l-l.3.4-oxadia2ole- I ll-3.4.5.64etrahrontohenzoic acid. Z|5-t2-chloro 3.5-dinitrophenylll .3.-l'oxadiazoleZ-ylI henzoic acid. llF-tZ.4-dichloro-lialinitrophenyll-l.3.4- outdiazole-lyll hemoic acid. Z-l5-t2-mcthyl-3.5- dinitrophenyll-l.K-Loutdiarolelyll henzoic acid. 2- [5 t3.4.5-trimctho\yphcnyll-l.l-i-oxadiamleJ-y|l hcnzoic acid. Z-|5%l-methylA-nitrophenyll l.3.4 osadiazolcl yll hcn/oic acid. 3454lmethyl-lnitrophenyll l.3.-l-o\adiazolcl-yli licnzoic acid. Z4541- methyl-5- l .3.4-oxadiazoleC-yl] hcnroic acid. 3-( 1.3.4-

dimethyl-3-furyl)-l.3.-1-oxadiazole-Z-yll benzoic acid. 2-l 5-! Z-n1ethyl-3-furyl)-l.3.4-oxadia7ole1-yll benzoic acid. Z-l5-(3-furyll-1.3.4-oxadiazoleJ-yll henzoic acid. 215'!-l-methyl-Z-[3-pyridyll- 5-thiazolyl)l.3.4- oxadiazoleQ-yl] benzoic acid. Z-lS-MpyridyH-I3.4- oxadiazolc-lyl] benzoic acid. 2-l5-t2-pyridyl)-l.3.4- oxadiazole-Z-yll benzoic acid. 2-[543-py'ridyll-l.3.4- (H'tltlltl70lC'2-yl] henzoic acid. and the like.

It is desired to emphasize that the herbicidal chemi cals employed herein are mono henzoic acid types. Also. a necesaary requirement for activity is the ortho carboxylic acid or carboxylate group.

As indicated. the invention is also concerned with novel methods of making certain new 2-( l.3.4 oxadizoleJ-yl) benzoic acid chemicals. One such new method. herein below refered to as Method la. involves the preparation of 2-(l.3.4-oxadiazole-2-ylj henzoic acids of the formula l l RA 0 COOH COOl-l (wherein R is as previously defined) is mixed with sulfur trioxide in dimethylformamide medium at a temperature of from -l() to 10, and thereafter the Z-( l.3.4- oxadiazole-Lyl) henzoic acid of the stated formula is recovered from the mixture. In the course of the reaction the elements of water are removed from the precursor. In this method the selection of the starting hydrazide chemical is critical. since otherwise similar chemicals. in which the value of R, is other than the values above stated. are inoperative. Also critical is the use of sulfur trioxide-dimethylformamide complex as the cyclizing agent. since numerous other common cyclizing agents are inoperative. Thus. such cyclizing agents as phosphorus oxychloride. thionyl chloride. polyphosphoric acid. etc. fail to accomplish cyclization. Also critical is the temperature at which the reaction is carried out. since at higher temperatures than those stated. very poor yields are obtained. The proportions of hydrazide starting chemical. sulfur trioxide and dimethylfornntmide are not critical and may vary widely. For example. for each mole of hydrazide starting chemical employed. there may he used from 1 mole to 3 moles or more of sulfur trioxide and from l0 moles to 15 moles or more of dimethylformamide.

In accordance with another method of the intention. hereinhelow referred to as Method It. the new chemical 2-( l.3.4-oxadiazole-2-yl) henzoic acid itself. is prepared according to a similar procedure. but employing fuming sulfuric acid as the agent to remove the elements of water and bring about cyclization. in this novel method the hydrazide chemical. l-benzo vl-2-( Z-carbosyphenyl) hydrazine.

COOl-l namely is mixed with firming sulfuric acid at a temperature of front to and thereafter the 3-( l.3.4- oxadiazolylQ-yl) benozic acid F coon c cal and fuming sulfuric acid are not critical and may 1 vary widely. For example. for each 100 parts by weight A derivative of benzhydrazidc (ll is heated with phthalic anhydride (ll) in an inert solvent to give a quantitative yield ofthe hydrazide (Ill) where R. is hydrogen or certain substituents. This hydrazidc (llll can be cyclized by dimethylformamide-sulfur trioxide compie): to two products. a phthalimido derivative (IV) or a Z-( l.3.4-oxadiazole-Z-yl) benzoic acid (V). The respective yields of these two products vary depending upon the R substituent. In some cases the yield of the l.3.4-oxadiazole (i.e. compound V) is zero. Pyrolysis of 2-( l.3.4-oxadiazole-2-yl) bcnzoic acids results in the formation of the phthalimido derivative (i.e. IV )l The phthalimido derivative IV] can be converted to hydra zide (ill) on treatment with aqueous base followed by neutralization with aqueous acid. and the hydrazide (Ill) can be recycled to (IV) and (V). The invention. in its first method aspect. is based on the discovery that when R is hydrogen (preferred) or is a substituent selected from Z-chloro. 4-chloro. Z-methyl. 3-niethyl or 4-methyl. the specific cyclizing agent (dimcthylformamidesulfur trioxide complex) unexpectedly produces the desired product (V), as indicated previously.

Method ll] Formula description:

T 1 COOH mm m 0 i COOH (IN/f1 of starting hydrazide there may be employed from 200 parts to 800 parts by weight or more of fuming sulfuric acid (or 100 parts to 400 parts by volume). The concentration of sulfur trioxide in the fuming sulfuric acid is conventional and usually ranges from 15 to per cent by weight.

it will be noted that in the foregoing methods the carboxylic acid group is present throughout Other methods useful for making chemicals employed in the invention. to be described below. include syntheses which involve a group such as methyl. chloromethyl. dichloromethyl. trichloromethyl. formyl. acetyl. ester. etc. which can be chemically converted to the carboxylic acid group when required.

The following are the methods of synthesis:

Method la:

Formula description:

OONHNHZ N-NHCO (VI) (VII) This method invohes the nitration of Z(5-phenyll.3.4-oxadiazole-lyll hCttlUlC acid (Y1) which was prepared by Method la. Nitration occurs exclusively in the 5phenyl ring. The nitro derivati es produced can be separated by crystallization.

Method l( This method of the invention is similar to that of Method lu except that fuming sulfuric acid is used to cyclize the hydrazide (llll lspecifically. R is hydrogen. i.e. l-t lcarboxybenzoyl)-2-benzoylhydrazineI to 24 5- phenyl-l.3.4-oxadiazole---yl) benzoic acid.

Method it] This method involves synthesis of esters. A 2-( 1.3.4- osadiazole-Z-yl) benzoic acid derivative in chloroform in the presence of an excess of thionyl chloride in refluxed till the evolution ofhydrogen chloride and sulfur COOH (III) I 0001-! o l dio\ide ceases. Alter the removal of chloroform and e\cess thiony l chloride the residue (the acid chloride of the oxadia7ole acid) is dissol ed in toluene or benzene and added to a solution of appropriate alcohol in tolu ene or hen/ene along with an organic base to act as hydrogen chloride acceptor. The mixture is washed with water. dilute acid. dilute bicarbonate. dried and the sol- \ent remm ed. The esters so produced are usually \iscous oils.

Esterification can also he brought about by diazoti Iation or by the reaction ol the sodium or potassium salt of an osadiazole acid with an alkyl halide.

Method II Formula description:

Method lllh This invention involves the hydrolysis of esters to their corresponding acids. The ester is hydrolyzed in comma 2 COCI NH NH I l R1 cs 1 (VIII) (IX) ll-N N N a l a l 0 i, g 0 1 in 1 Ben7hydrazide deri atlve t It is reacted with o-toluoyl chloride (Yllll to produce laroyl-Z-o-toluoyl hydrazine (IX) which can he cyclized to a Z-aryLS-o-tolyl- 1.3.4-oxadiazole (X) by any of the standard cyclizing agents reported in the literature. The methyl group lCHi) on the diphenyloxadiazole (X) can he converted by permanganate oxidation to form a 2-(5-phenyl- 4U Methnd IV l.3,Lounliazole-Z-ylt henzoie acid (V). This method involves the chlorination of 2-(5-phenyl-l.3.4-oxadiazole-2-yl) benzoic acid (VI) to 2-(5- chlorophenyll .3.4-oxadiazole-2-yl) benzoic acid. Method lllu 45 Formula description:

Method Va This method describes the oxazole synthesis.

COCH R 2 2 Brz copim or Br N. B. S?

R O coon 3 R -CH NH I I c0 (30 n-cnco- 2 H01 5 1 R 3 0 R l l coon H230;

7S solving the chemicals in a stoiehiometric amount of an An acetophenone (D) is brominated to the corresponding bromide lE) which in D.M.F. is treated with an analog ofpotassium phthalimide (F) to give the cor responding phthalimide (G). Subsequent ring opening with dilute base followed by acidification affords a phthalamie acid (H). Ring closure with concentrated sulfuric acid at room temperature will give a Z-(Z- oxazolyl) benzoic acid (J).

Method VI] The synthesis of the esters of oxazole herbicides may follow standard literature procedure for aromatic ester preparation. The oxazole acid may be refluxed in an cess of appropriate alcohol in the presence of an acid catalyst.

Turning now to the use of the chemicals herein described as herbicides. the method of formulating and using the herbicidal compositions may follow conventional practice and in general involves controlling weeds by applying to a locus containing weed seeds or supporting weed growth a herbicidally effective amount of the chemical.

The herbicides of the invention may be applied before or after crop and/or weed emergence. The chemicals may be applied to the soil or plants in various forms as described below. The chemicals may be impregnated on finely-divided or granular inorganic or organic carriers such as attapulgite clay. sand. vermiculite. corn cobs. activated carbon and other granular carriers known to the art. The impregnated granules may then be spread on the soil. A wettable powder can be prepared by grinding the chemical to a fine powder and mixing it with an inactive powdered carrier to which a surface active dispersing agent has been added. The wettable powder may then be dispersed in water and sprayed on the soil or plants. An emulsifiable concentrate may be prepared by dissolving the chemicals in a solvent such as acetone. benzene. toluene. ethanol. or other aliphatic or aromatic hydrocarbons to which a surface active dispersing agent has been added. The emulsifiable concentrate may then be dispersed in water and sprayed on the soil or plants. Solutions of the chemicals (not the esters) can be prepared by disappropriate base such as potassium hydroxide. ammo nium hydroxide. sodium hydroxide. or diethanolamine.

The salts formed by such a process are then soluble in water and with the addition of a surface active \vetting agent may be sprayed on the soil or plants. Surface active agents as described above are well known to those skilled in the art and reference is made to McCutcheon's Detergents and Emulsifiers. I970. Allured Publishing Corp. Ridgewood. New Jersey; also Hoffman et al. U.S. Pat. No. 2.614.916. columns I to 4 or 2.547.724. columns 3 and 4.

Two specific advantages ofthe present compounds as herbicides are:

l. Control of (Ivpcruccm' spp. Currently there are few selective herbicides for the control ofthese species. Purple nutsedge ((ypvrux rommlux L.) is said to be the worlds worst \veed.

Efficacy as a selective herbicide in cranberry. There are few herbicides for this use.

The following examples. in which all quantities are expressed by weight unless otherwise indicated. will serve to illustrate the practice of the invention in more detail.

EXAMPLE 1. METHOD lu Step l. l-Benzoyl-ZJZ-carboxyphenyl)hydrazine At a temperature of about 18. powdered benzhydraride 4 [26 g. 1 mole) was suspended in stirred benzene (1.6 l). and 24-mesh phthalic anhydride (148 g. 1 mole) was added portionwise over 15 to 20 minutes. After the addition the reaction mixture was stirred for a further hour. The product. l-benzoyl-2-(Z-carbosy phenyllhydrazine (lll) lR =H) was collected on a filter. pressed free of benzene and air dried. 276 g 98%. M.P. 2()5-2()8.

Step 2. Z-(S-Phenyl-l.3.4-oxadia7oleQ-yl) benzoic acid.

Dry dimethylformamide (D.M.l-.) (300 ml) was cooled in an ice-bath and with stirring treated dropwise with sulfur trioxide (S( ,'tl l()() ml) such that the temperature did not exceed 5. With continued ice-bath cooling the D.M.F./SO complex was treated dropwise with a solution of l-bemo)l-2(2-earboxybenzoyl)hydrazine (148 5 g. 0.52 mole) dissolved in dry D.M.F. (200 ml). After the addition. the reaction was stirred for a further 2 hour at and then for several hours with the ice-bath removed. The reaction mixture was poured into water (2 l) and allowed to stand until the paste which separated became hard. The crude product was collected on a filter. washed well with water. then air dried. wt. 143 g. This crude product was stirred into a solution of sodium bicarbonate (150g) in water( 1.4 1) till all ett'crvescence had ceased. L ndissolved mate rial was collected on a filter. washed with water and air dried. 26 g (18 Recrystallization from methanol ga\e white crystals of N-phthalimidohenzamide. (1V) (R H 1. M.P. 215 218.

Acidification of the bicarbonate extract gave a precipitate which was collected on a filter. washed with water and air dried. l 16 g (821). A portion was recrystallized from acetone to give 2-(5-pheny1-1.3.4- oxadia/ole-2-y1)benzoic acid (V) (R 'H M.P. l72.6.

Analysis gave C. 67.55; H. 3.75; N. 10.26. c.,-,H...N.o.. requires C. 67.66; H. 3.79; N. 10.52.

Step 3. Conversion of N-phthalimidobenzamide to 1-hen2oyl-2-( 2carboxybenzoyl )hydrazine NPhthalimidobenzamide (353 g. 1.32 mole) was dissolved in a slight excess of 2N sodium hydroxide solution After filtering. the reaction mixture was poured into 2N hydrochloric acid. The precipitate. l-benzoyl- 2-( learboxybenzoyl)hydrazine was filtered. washed with water and air dried. wt. 368 g.

EXAMPLE 2. METHOD 11 Step l. l( 2-Chlorobenzoyl 2 2'toluoyl)hydrazine o-Chlorobenzhydrazide (80 g. 0.47 mole) was sus pended in hem'ene l l) to which was added pyridine (38.2 ml). With vigorous stirring. the suspension was treated dropwise with o toluoy1 chloride (74.5 g. 0.48 mole) and on completion the reaction was heated to reflux over 2 hours. After cooling. the product was filtered and washed with water. Recrystallization from 75 ethanol ga e l( 2-ch1orobenzoyl )2-( 2- toluoyl)hydrazine (1X) (R o-CI) 107.5 g. 7991. M.P. mamas".

(Found: C. 62.94; 62.97; H. 4.73. 4.74; N. 9.57. 9.54. C.,-.H. CIN O requires C. 62.39: H. 4.54; N. 9.90).

Step 2. 2-(2-Chlorophenyl)-5-(2-tolyl)-1.3.4- osadiamle Dry D.M.F. (160 ml) was cooled in an ice bath and with stirring treated dropwise with 50;; (55 ml) such that the temperature did not exceed On completion the D.M.1-.-SO;. complex was treated with a solution of 1( 2-ehlorobcn7oylh2- 2-toluoyl)hydrazine (1X) (R =o Cl) (87.5 g. 0 3 mole) dissol ed in dry D.M.F. 170 ml). The reaction mixture was stirred in the icehath for 1 hours. then heated on the steam hath till i tion of potassium permanganate (38 g. 0.24 mole) in water (500 ml). The mixture was heated to reflux. Refluxing was continued till the color of the permanganate had discharged. The reaction mixture was filtered hot and the manganese dioxide on the filter was washed with hot water 100 ml). then extracted with cold acetone. Remoyal of the acetone yielded starting material 13 g after recrystallization).

The combined aqueous filtrate was acidified. extracted with ether and the ether extract washed with water and dried. Evaporation of the ether left an oil which slowly solidified. 1.5 g. 9.6% (based on amount of (X) (R =o-Cl) consumed). Recrystallization from acetone gave 2| 5-( 2-ch1orophenyl l .3.4-oxadiazole 2-y11 henzoic acid (V) tR qi-Cl). M.P. 142144.

(Found. C. 59.77. 59.68. H. 3.28. 3.10; N. 9.17. 8.84. C,.-.H ClN O;, requires C. 59.91; H. 3.02; N. 9.32.)

EXAMPLE 3. METHOD 1h 2-1 5( 2-Nitrophcnyl l .3.4-oxadiazolc-2yl I benzoic acid and 2-I5-(3-nitrophenyl)-1.3.4-oxadiazole-2-yl)- benzoic acid.

Finely-powdered 2-(5-phenyl1.3.4-oxadiazole-2-y1) benzoic acid (V1) 133 g. 0.5 mole) was added portion wise to stirred concentrated sulfuric acid (200 ml) kept cool in an ice-bath. On completion. the mixture was treated drop-wise while stirring with a solution of concentrated sulfuric acid (42 ml) in nitric acid (42 ml. 5.6. 1.42) such that the temperature did not exceed 5. After the addition. the reaction mixture was stirred for a further 2 hours in the ice-bath and then poured into cold water (4 l). The yellow solid which precipitated was filtered. washed well with water. and air dried. 143

A 10 g portion of crude product was stirred in cold methanol (100 ml) for 1 /2 hours. Undissolved material was collected and dried. 6.5 g. The mother liquor was concentrated to 50 ml to give a second crop of 1 g. Two types of crystals separated when the mother liquor was concentrated to 25 ml. The amber-coloured crystals were hand picked to yield 0.8 g of material which was recrystallized from methanol to give 2-(5(2-nitrophenyl)-1.3.4-oxadiazole-2-yl] benzoic acid (V11) (R, o-NO- M.P. 182187. Yield estimated at about (Found: C. 57.96. 57.42. H. 2.97. 3.07. N. 13.51. 13.52. C..-.H..N;.O requires C. 57.88; H. 2.91; N. 13.50.)

The remaining light yellow crystals were combined with the other two crops and recrystallized from acetone to gi e 2-(5 3-nitrophenyl)-1.3.4-oxadiazole- 2-yl] benzoic acid (V11) (R,=(m-NO- M.P. 222226. Yield estimated at -90%.

(Found: C. 57.94. 58.06; H. 2.96. 3.00; N. 13.64. 13.49. C..-,H.,N;,O.-. requires C. 57.88; H. 2.91; N. 13.50.)

EXAMPLE 4 METHOD if 2-(5-Phenyl-1.3.-loxadiaZoIe- -yI) benzoic acid Fuming sulfuric acid ml) (20)? was cooled in an ice/salt bath. then w ith vigorous stirring treated portionwise with powdered l-(2-carboxybenzoyl)-2-benzoylhydrazine (113.6 g. 0.4 mole) such that the temperature did not exceed 0 (time of addition. 15-20 mins) On completion of the addition. the reaction mixture was stirred for a further 1'4 hour. then poured into ice water. The precipitated solid was filtered.

washed with water and digested with aqueous sodium bicarbonate. The undissolvcd material was collected. washed with water and dried. to give N- phthalimidobenzamide. M.P. 2102l4. 13 g.

Acidification of the aq. bicarbonate solution gave 2- (5-phenyl-1.3.-l oxadiazole-2-yl) benzoic acid. which was filtered. washed with water and dried. M.P. l63l70. 84 g. 799?.

EXAMPLE 5 METHOD lllu.

Step 1. Phthalamic acid With vigorous stirring. concentrated ammonia solution (900 ml. 5.6. 0.9) was treated portionwise with phthalic anhydride (600 g. 4.0 moles) over a period of We hrs. After the reaction mixture had cooled to room temperature. the precipitated ammonium phthalamate was filtered. then dissolved in the minimum of water. When this solution was acidified to pH 2. phthalamic acid began to crystalize. M.P. l32136.

Acidification of the ammoniacal mother liquor gave a 2nd crop. Total weight of product. 551 g. 787.

Step 2. Methyl 2-eyanohenzoate Phthalamic acid (240 g. 1.37 moles) in methylenechloride 1.7 l) was stirred and cooled to 5 in an ice bath. Triethylamine (244 ml. 176 g. 1.74 moles) was added and a clear solution was obtained. Methyl chloroformate (200 g. 163 ml. 2.1 moles) was added at such a rate that the temperature did not exceed 5. As the addition continued. triethylamine hydrochloride precipitated and carbon dioxide was evolved. On completion of the addition. the ice bath was removed and stirring was continued for 12-20 hrs. at room temperature. Triethylamine hydrochloride was removed by filtration and the methylene chloride evaporated. The residue was dissolved in ether (21). and this ether solution washed with water. dried over anhydrous sodium sulfate and evaporated. Distillation under reduced pressure gave methyl Z-cyanobenzoate. b.p. 125 at 2.5 mm. 215 g (979? a solid at room temperature. M.P. 4546.

Step 3. Methyl 2-(5-2H-tetrazolyl)benzoate Methyl 2-cyanobenzoate (54 g. 0.33 mole) in D.M.F. (165 ml) was treated with sodium azide (23.4 g. 0.36 mole) and ammonium chloride (19.3 g. 0.36 mole) After the reaction mixture had been stirred on the steam bath for hrs.. the D.M.F. was removed under reduced pressure and the residue dissolved in water (200 ml). The solution was filtered. cooled in ice and acidified to give a white precipitate which was filtered. washed with water and dried. This gave methyl 2-(5-2H-tetrazolyl)benzoate. M.P. l32l35. 19 g (28% (Found: C. 53.79.5259. N. 26.79. 26.84. 27.25. C,,H,. 3.95; N. 27.44.)

Step 4. Methyl oxadiazole-Z-yl]benzoate Methyl 2-(S-ZH-tetrazolyl)benzoate (2 g. 0.01 mole) in pyridine (30 ml) was treated with p-nitro-benzoyl chloride (3.6 g. 0.02 mole). Heat was emitted and a white precipitate appeared. Heating on the steam bath produced a homogeneous reaction mixture and effervescence occurred. After /2 hour. gassing ceased. the reaction mixture was cooled. treated with a few drops of water and allowed to stand for 15 mins. Addition of water (500 ml) gave a light yellow precipitate which was collected. washed with water and dried. Recrystal- 2.33; H. 4.25. 4.17. 4.07. 0 requires C. 52.94; H.

2-[ 5-(4-nitrophenyl l .3.4-

lization from acetone gave yellow crystals of methyl 2- l5-(4-nitrophenyl1-1.3.4-oxadiaZole-2-yll benzoate. M.P. l172. 2.2 g. 70%.

(Found: C. 59.08; H. 3.50; N. 12.76. C H N O re quires C. 59.08. H. 3.41; N. 12.92.)

EXAMPLE 6 METHOD V Step 1. N-alpha-Methylphenacylphthalimide To a stirred solution of 2-bromopropiophenone (21.3 g. 0.1 mole) in D.M.F. ml) was added portionwise over 10mins. potassium phthalimide (20 g. 0.12 mole). The temperature rose slightly and after stirring for 3 hours the reaction mixture was poured into water (600 ml). The yellow precipitate was collected. washed with water and dried. Recrystallization from ethanol gave N-alpha-methylphenacylphthalimide. M.P. 82-84. 21.5 g. (7771).

Step 2. Nalpha-Methylphenacylphthalamic acid N-alpha-Methylphenacylphthalimide (27.9 g. 0.1 mole) was added to l N sodium hydroxide ml) and stirred for 24 hrs. The resulting solution was liltered and poured into stirred N/2 hydrochloric acid (240 ml). N-alphaMethylphenacylphthalamic acid was collected. washed with water and dried. M.P. 132-l36, 20.3 g. (689? Step 3. 2-(4-Methyl-5-phenyl2-oxazolyl) benzoic acid N-alpha-Methylphenacylphthalamic acid (203 g. 0.068 mole) was added portionwise to cone. sulfuric acid (50 ml) over 15 mins. during which time the temperature rose to 40. The reaction mixture was stirred for 24 hrs. then poured into ice water (500 mi The resulting precipitate was filtered. washed with water and digested with aqueous sodium bicarbonate. Acidification of the aqueous bicarbonate solution and crystallization from water/ethanol 1:1) gave 2-(4-methyl5 phenyl-2-oxazolyl) benzoic acid. M.P. 188-190. 12 g. (637:

(Found: C. 72.07. 72.1 1; H. 4.83. 4.77; N. 4.99. 4.98. C H NO requires C. 73.3; H. 4.66; N. 4.06.)

EXAMPLE 7 METHOD ll) 2-(5-Phenyl-1.3.5-oxadiazole-2-yll benzoic acid Benzoyl chloride (2.8 g. 0.2 mole) was added dropwise to a solution of methyl 2 (5-2H-tetrazolyl) henzoate (2 g. 0.01 mole) in pyridine (30 ml). Heat was emitted and a precipitate of pyridine hydrochloride ap peared. Heating on the steam bath caused the evolution ofnitrogen. After /2 hour. all effervescence had ceased. the reaction mixture was cooled. a few drops of water added and the reaction allowed to stand 15 mins. An oil was obtained when the reaction mixture was added to cold water (500 ml). This oil was dissolved in ether. The ether extract was washed with dilute acid. dilute bicarbonate solution and water then dried over anhy drous sodium sulfate and evaporated.

The crude oil so obtained was dissolved in methanol (20 ml) and added to a solution of sodium hydroxide (0.5 g) in methanol (20 ml). After this solution had been stirred at room temperature for l hour. the methanol was removed. the residue dissolved in water. washed with ether and acidifed. The solid which precipitated was filtered. washed with water and dried. 1.5 g (56%) of crude product was obtained. Recrystallization front ethanol gave 2( 5-phenyll .3.4-oxadiazole- 2yl) benzoic acid. M.P. l77. The infrared spectrum was identical to that of 2-( 5-phen vll.3.4

O\'tlLllL17( lk 2 \'ll henzoic acid. made by methods la. 1( and 11.

EXAMPLE 8 Method 11 2( 5'Phenyl-l.3.-l oyadiazole-2yl) henzoic acid 2-Pheny1-5-(2-tolyl )-l .3.4-oxadia7.ole (47.2 g. 0.2 mole) was added to a solution of potassium permanganate (75 g. 0.47 mole) in water (875 ml) and refluxed till the color of permanganate had discharged. The re action mixture was filtered hot and the manganese dioxide collected on the filter was washed with hot water (100 ml). After cooling. the combined filtrates were acidified and extracted with ether. The ether extract was washed with water. dried over anhydrous sodium sulfate and e aporated to leave a white solid. Recrystalli7ation from methanol gave 2-(5phenyl-1.3.4 oxzalialole-l-yli henzoic acid. M.P. 173l75. 3.8 g (7.1); The infrared spectrum was identical to that of 2-( 5-phenyl-l.3.4-oxadiazole-2-y1) henzoic acid prepared by Method lu.

EXAMPLE 9 METHOD lllb EXAMPLE 10 Method lllh 2i 5-( 3.5-Dimethylphenyl l .3.4-oxadiazole2-yll hemoic acid c.1'. Example 7. Method lllh Methyl 2-(5-2Htetrazolyl) mole) Pyridine (60 ml) Sodium hydroxide (2 g) in methanol 100 ml) 3.5Dimethylhenzoyl chloride (6.5 g. 0.0-) mole) 2-| 5-( 3.5-Dimethylphenyl)-l.3.4-oxadiazole-2-ylI henzoic acid. M.P. 1621h4 (benzene). wt. 2.8 g (48% henzoate (4 g. 0.02

EXAMPLE 11 METHOD lllu Methyl 2-13.5-diehloro-4anis)'ll-l.3.4-oxadiazole- -yll henzoate (:1. Example 5 Methyl 2-(5-2H-tetrazolyl) henzoate (3.75 g. 0.018

mole) Pyridine ((10 ml) 3.5-Dich1oro-4-anisoyl chloride (9 g. 0.036 mole) Methyl 2l 5-(3.5-dichloro-1-anisyl)-1.3.4- osadiazole-Z-yl] henzoate, M.P. 153-157 (ethanol). wt. 5 g (57 1).

EXAMPLE [2 METHOD lllu Methyl 2-15 14-methyl-2-t3-pyridyl)-5-thiazolyl-l .3.4-oxzaliazole-2y11 henzoate et'. Example 5 Step 4.

The precipitated crude product was washed with water and aqueous bicarbonate solution.

Methyl 2-(5-2H-tetrazolyl) henzoate (4 g. 0.04

mole).

Pyridine ml) 4-Methyl-2-( 3-pyridyl )-5-thiazolylcarbonyl chloride hydrochloride (9.7 g. 0.04 mole) Methyl 2-[5-[4anethyl-2-t3-pyridyl)-5-thiazolyl1- 1.3.4.-oxadiazole-2-y1l benzoate.

M.P. 152153 (ethanol). wt. 1.8 g (2471 EXAMPLE 13 Method 111!) 2-l5-(2.4-Dich1orophenyl)-1.3.4-oxadiazole-2-y11 henzoic acid c.f. Example 7. Method lllb Methyl 2-(5-2H4ctrazolyl) henzoate (10.5 g. 0.05]

mole) Pyridine (150 ml) 2.4-Dichlorobenzoyl chloride (21.0 g. 0.1 mole) Sodium hydroxide (3 g) in methanol (200 ml) 2-!5-(2.4-Dichlorophenyl)-1 .3.4-oxadiazole-2-yl l benzoic acid. M.P. l68-171. wt.. 5.5. g(317() EXAMPLE 14 METHOD 111a EXAMPLE 15 METHOD 1| 2-[ 5( 3-Ch1orophenyl 1 .3.4-oxadiazole-2-yll zoic acid c.f. Example 2 2-( 3-Ch1orophenyl)-5-( 2-tolyl1- 1 3.4-oxadiaz0le (54 g. 0.2 mole) Potassium permanganate g. 0.47 mole) in water 1 l Recovered starting material (27 g) ben- 2-15-(3-Ch1orophenyl)-1.3.4-oxadiazo1e-2-yll benzoic acid. M.P. 184-188. wt. 1.0 g (3.3%).

EXAMPLE 16 METHOD 1a 2-l5-(4-Chlorophenyl)-1.3.4-oxadiazole-2-yl] benzoic acid c.t. Example 1. Method la Sulfur trioxide (50 g. 35 ml) in D.M.F. (ml) 1- (4Chlorohenzoyl )-2-( 2-carboxyhenzoyl hydrazine (-15 g. 0.15 mole) in D.M.F. (75 ml) 2- 15-(3'Chlorophenyl) oxadiazole-2-y1] benzoic acid. M.P. 20n-209 (acetone). wt.. 9 g (21% (Found: C. 59.09. 58.88. H. 3.03. 2.97: N. 8.16. 8.16; C1. 1148. 10.94. 11.32. 11.51 c sHgclNgog requires. C. 59.91; H. 3.02; N. 9.32; CI. 11.79)

EXAMPLE 17 METHOD In 2[5-(2-Tolyl)-1.3.4-oxadiazole-2-yl] benzoic acid ct. Example 1. Method la Sulfur trioside (250 g. ml) in D.M.F. (500 m1) (150 g. (H) mole) in D.M.F. (200 ml]. Z-l5-(l'lolyl|-I.3.4-oxadiazole-2-yl| benzoic acid. M.P. l54-l55 (acetone/BO-65 ligroin). wt. 33.5 g l4.2 J.

(Found: C. 67.73, 67.78; H. 4.72. 4.3l; N. 8.7L 8.67. 5

C H NJ); requires C. 68.56; H. 4.32: N. 10.00.]

EXAMPLE [8 METHOD ll Z-IS-(Z-Anisyh-l.3.4-oxadiazole-lyll henzoic acid cf. Example 2 ll 2Anisyl-5-(Z-tolyl)-l.3.4-oxadiazole (26 g. (Ll mole) Potassium permanganate (37.5 g. (L24 mole) in water (450 ml) Recovered starting mate rial 18 g) Z'[5-(2-Anisyl)-l.3.4-oxadiazo|e-Z-yll benzoic acid.

M.P. l57-l6tl (benzene/ethanol) wt. l.7 g. (17.9); (Found:('.66.22.65.42;H.4.46.4.46;N.9.63.9.97.

C H N O. requires C. 64.86; H. 4.08; N. 9.46.)

EXAMPLE 1) METHOD ll (rtmna; (7. 62.83.6171: H. 3.64. 3.47; N. 16.17.

16.05. C H N O; requires. C. 62.92; H. 3.39; N.

EXAMPLE 21] METHOD ld Ethyl 2-( 5-phenyl-l.3.4-oxadiazole-lyl) benzoate 2(5-Phenyll.3.-1 oxadiazole-2-yl) benzoic acid (26.6 g. 0.1 mole) in chloroform 100 ml) and thionyl chloride (20 ml) were refluxed for l hour. The excess thionyl chloride and chloroform were removed under reduced pressure to leave a colorless oil which slowly solidified. Benzene 100 ml) was added. The resulting solution was added dropwise to a stirred solution of ethanol (6 ml. 0.1 1 mole) and pyridine l0 ml) in benzene (200 ml). After l2 hours. an equal volume of ether was added. The solution was washed with water (5H1) ml) N/5() HCl (500 ml). 592 aq. bicarbonate (500 ml) and again with water (500 ml). Evaporation of the ether left a light yellow viscous oil which could not be distilled 23 g (78% EXAMPLE 2] Methyl Z-(S-phenyl-l.3.4-oxadiazole-2-yl) benzoate Z-(S-Phenyl-l.3.4 oxadiazole-2-yl) benzoic acid (l5 g. 0.056 mole) in dry ether (700 ml) was treated with gs ethereal diazomethane till the color of the ethereal di- EXAMPLE 22 65 Propargyl 2 5-phenyll .3 .4-oxadiazole-Z-y|) bcnzoate Z-(S-Phenyl-l.3.-1-oxadiazole-Z-ylJ benzoic acid (26.6 g. 0.1 mole was added to a solution of potassium hydroxide (6 g. ().ll mole) in methanol (250 ml). When all the acid had dissolved. propargyl bromide (21) ml) was added and the reaction mixture refluxed for 2V2 hours. The solvent was removed. the residue was dissolved in ether which was subsequently washed with water. aqueous bicarbonate. again with water and dried. Removal of the ether gave a light brown solid which was recrystallised from ether. This gave propar gyl 2-( 5-phenyl l .3.4-oxadiazole-Zyl) benzoate as tancolored crystals. M.P. 9)-llll. [[5 g (38');

(Found: C. 71.43. H. 4.04; N. 9.37. (NH|2N2();| requires. C. 71.04; H. 3.98; N. 9.2L)

EXAMPLE Z3 Methyl 2-|5-(3-nitrophenyl)-l.3.4-oxadia7oleQ-yl| benzoate of Example 22 2-l5-(3-Nitrophenyl)-l3.4-loxadiazoleQ-yl] benzoic acid (3].l g. ().l mole) Potassium hydroxide (5.6 g. 0.1 mole) in methanol (600 ml) Methyl iodide l7 ml) Methyl Z-[5-nitrophenyl)-l.3.4-oxadia7ole-l-ylll benzoate. M.P. l32l34 (methanol). \vt. 33.5 g (970? (Found: C. 59.3). 58.72; H. 3.52. 3.34: N. l3.l5.

12.9l. C H NJ); requires C. 57.5l. H. 3.54; N. 13.42.)

EXAMPLE 24 2.3-Epoxypropyl Z-(5-phenyl-l.3.4-oxadia7oleJ-ylI benzoate c.f. Example 22. same quantities. epibromohydrin (l5 ml) as alkylating agent. The product. 3.3- epoxypropyl 2-( S-phenyll .3.4-oxadiazoleJ-yl benzoate was a viscous oil which could not be distilled. wt. 12 g (37% EXAMPLE 2.

Butyl 2-( S-phenyll .3.-1oxadiazole-2yl) benzoate ct. Example 20. same molar quantities. n-butanol 6. wt. 25 g (saw EXAMPLE 26 Oetyl 2-(5phenyl-l .SA-oxadiazole-Z-yll benzoate c.f. Example 20. n-octanol (12.5 g. 0.] mole) used. The product. n-octyl 2-(5-phenyl-l.3.4-oxadiazole Z-yl) benzoate was a viscous oil. wt. 28 g (74% EXAMPLE 27 Docecyl Z-(S-phenyl-l.3.4-oxadia2olc'2-ylJ benzoate c.f. Example 20 Dodecyl alcohol (l8.6 g. 0.] mole) Dodecyl Z-(S-phenyl-l.3.4-oxadiazoleZ-yl) benzoate, a viscous oil. wt. 35 g (81)? EXAMPLE 2H 3-Butynyl Z-(S-phenyll .3.4-oxadiazole-2-yl) bemoate cf. Example 20 3-Butyne-l-ol (7 g. ().l mole) J-Butynyl 2 (5-phenyl-l.3.loxddiazoleQ-yll benzoate. a viscous oil. wt. l2 g (38% EXAMPLE :9

Method 'h Methyl 2-( -phenyl-I-oxazolyl) benzoate Z-( 5-Phcnyl-Z-oxa7olyl) benzoic acid (5g. 0.02 mole) in methanol (5t) ml) and cone. sulfuric acid (05 ml) was refluxed )6 hours. The methanol was removed and the residue dissolved in chloroform. The chloroform solution was washed with dilute bicarbonate soluticn. water. then dried and evaporated. Rccrystallisation of the residue from ethanol gave methyl 2'(5-phenyl2-oxazolyl) benzoate. M.P. 7779. wt. 3 g (57% (Found: C. 73.16. 73.40; H. 4.77. 4.72. N. 4.95. 5.00. H NO requires C. 73.ll; H. 4.691N. 5.02.)

EXAMPLE 30 Ethyl Z4S-phenyl-Z-oxazolyl) benzoate cf. Example 29 2-( Phenyl-Z-oxazolyl) benzoic acid g. 0.04 mole) Ethanol 100 ml) cone. sulfuric acid (10 ml) reflux time '10 hours Ethyl Z-t5-phenyl-2-oxazolyl) 49-5() (ligroin) wt. 8 g (72% (Found: C. 73.86. 73.99. H. 5.27. 5.20; N. 4.70. 4.85;

requires C. 73.80; H. 5.11; N. 4.78.)

EXAMPLE 3] n-Butyl 2-(S-phenyl-Z-oxazolyl benzoatc cf. Example 29 245-Phenyl-2-oxazolyl) benzoic acid (l() g. 0.04

mole) n-Butanol (100 ml). cone. sulfuric acid (0.5 ml) Heated on steam hath hrs.

n-Butyl 2-(5-phenyl-Z-oxazolyl) benzoate. a viscous light yellow oil. wt. l(l.5 g (90% EXAMPLE 32 benzoate. MP

Propargyl Z-yll benzoate c.f. Example 22 2-[54 K-Nitrophenyl)l.3.4 oxadiazole l-yl| benzoic acid (3l.l g. ().l mole) Potassium hydroxide (b g. ().ll

mole) in methanol (25() ml) Freshly distilled propargyl bromide (20 g) Propargyl 2-[ 5-( 3nitrophenyl l .3.4-oxadiazolelyljl benzoate. MP. lZ-l-l26. wt. )2 g (34% (Found: C. 61.87.61.751 H. 3.43. 3.33; N. 12.64. lZJl; C H N O requires C. M90. H. 3.16: N. 11.00.)

EXAMPLE 33 Methyl ll 5( lnitrophcnyl l JA-oxadiazole-Z-yll benzoate.

Z-I 5( lNitrophenyl l .3.4-oxadia7ole 2-yll benzoic acid (3i g. 0.] mole) in acetone (1 l) was treated with u dimcthyl sulfate [U ml) and anhydrous potassium carbonate )5 g). The reaction mixture was refluxed and stirred for EU hours. After the removal of the solvent. the residue was treated with water. and the undissolved material filtered. washed with water and dried. Recrystallisation from acetone gave methyl 'l-[5-(2nitrophenyl )-l .3 .4-oxadiazoleZ-yl I benzoate. M .P. lo5-l(w9. 5 g.

EXAMPLE 34 Z-l5-(4-Nitrophenyl)-l.3.4-oxadia2ole-2-ylI benzoic acid Crude reaction product from a repeat run of Example 5 was dissolved in methanol (25 ml) and stirred for 2 hrs. in a solution of sodium hydroxide (0.75 g) in methanol (50 ml). Methanol was then removed and the residue was dissolved in water. extracted with ether to remove unreacted ester and acidified. The precipitate was filtered. washed with water and dried. This gave 2- [5-(4-nitrophenyl)-l.3.4-oxadiazole-2yll benzoic acid M.P. Zl52l7, 0.8 g. 1.6 G of methyl ester was ob tained from the ether extract.

EXAMPLE 35 To illustrate effectiveness as preemergence herbicides. 150 mg chemical may be dissolved in 5 ml acetone and optionally 30 mg of conventional emulsifying agent (cg. isooctyl phenyl polyethoxy ethanol; nonionic surfactant. condensation product of phenol hav ing isooctyl side chain with about 9 moles of ethylene oxide; also called alpha-(p-( l.l.3.3.-tetramethylbutyl) phenyl l-omega-hydroxypoly[oxyethyleneI The final volume may be increased to 300 ml with distilled water, making a 500 ppm solution. One hundred and sixty milliliters of a 250 and 125 ppm solution are prepared by diluting 80 and ml of the 500 ppm solution with and ml of distilled water. respectively. The chemi cals are applied by drenching 80 ml of the respective solutions on the surface of soil in 6-inch plastic pots which had been planted with the following weeds and crops'. common lambsquarters (Cherwpodium album L. rough pigweed (Amaranllms relroflexus L.) purslane (Portulaca oleracea L.). large crabgrass (Digi'raria .ranquinalis (L.) Scop.). barnyardgrass (Echinor'hloa r'rusgalli (L.) Beauv.). giant foxtail (Setaria faberii Herrm. corn (Zea mavs L. cotton (Gossypium hirsulum L.). and soybeans (Glycine max (L.) Merr.). Two seeds of each crop are planted on the diameter one inch below the soil surface in greenhouse soil (3 parts loam and l part sand). A mixture of the above mentioned broadleaf weeds is planted on the surface of one-half of the pot. and a mixture of the above mentioned grass weeds is planted on the surface of the remaining half. The weed seeds are then covered with a thin layer of soil. There are two replications per treatment. 8O milliliters of the 125. 250 and 500 ppm solu tions, drenched on the soil surface in a 6-inch pot. is equivalent to 5. l0 and 20 lbs/A. The pots are then subirrigated. The results are recorded l4 days after treatment and are reported in Table l.

The results of this test indicate that the oxazoles and oxadiazoles are effective preemergcnce herbicides. (The rates of application employed in this dosage response example extend to rates higher than necessary in typical agricultural use. with consequent greater crop injury. Selectivity of the chemicals as herbicides is demonstrated in subsequent examples at lower dosages.)

The results also indicate that the substituents of the benzoic acid must be attached at the two position of the benzoic acid in order to have herbicidal activity. In Table 1 (Part B) compounds (A). (13) (C). (D). (E) and (F). which have the substituents at other than the two position. are outside the invention and are inactive as herbicides; whereas. the other compounds in the test have the substituents at the two position and are active as herbicides. The dibenzoic acid compound (G) is likewise inactive and is outside the invention.

Table l (Part A) oxa/oles and oxadia/ules.

Percent Control Percent lnjun Rate Bruad- 80 Compound Lh/A Leaf (irasx (urn Cotton hean 24 5-phenyll .3,-Z-uxa 5 85 XX 20 90 R diaIolc-Z-yllhenmic l0 )3 93 0 I00 Ml acid Ill 90 93 41) IOU 9U 2-[5-lZ-chlnrophcnyll- 5 7t) 55 0 6t) 1.3.4-nxadia/ole-I-yl| I0 70 b0 20 H0 20 henloic acid 20 R0 70 20 80 90 2-I5-(3-chloruphen tl|- 5 75 70 0 50 0 IJA-oXadia/ulc-Z-yl] It) 75 75 20 90 80 benvoic acid It) )0 R0 I00 100 Z-IS-I-i-chlorophcnyll- 5 9O 80 (l 100 60 l.3AmxadiamIe-I-yl| l0 J0 90 0 I00 90 henmic acid 20 95 90 40 MK) 90 1-] 5-( Z-tolyl l JA- 5 9U )0 H 8U 6U oxadiazole-I-yl] hen/oil; l0 )0 88 I0 I00 5() acid 2U 9t] 90 It] HK) Kl) Z-[5-i Z-anisyl l-Ll-l- 5 50 R0 20 K0 ht) OXadiu/olc-Z-fll hcn/oic Ill 60 K0 0 (all 20 acid 30 75 85 20 I00 60 2-! 5-( Smitmphenyll- 5 5t] 0 0 0 LJA-oXadiaIoIc-Z- II I0 55 55 0 (l 0 hen/oic acid 20 0 (I 0 l-[5-(3-pyrid ll-l 3.4- 5 40 20 0 I00 40 oxadiuzuIe-Z-yll henvoic I0 n0 (1 70 b0 acid 20 till K0 (1 70 70 2-[5 (34.5-trimethyl- 5 20 I0 0 60 0 Z-l'uryl )-l .3 -l-oxadia- I0 30 35 0 60 20 /0le-2- \l|hen/oic acid 20 30 40 20 I00 20 24 5-phenyl-2'oxaml 5 20 t) 20 hcnzoic acid [0 50 N5 40 80 40 2 71) hi) llXl IOU Il-hutynyl 2(5-phenyli0" 92 I .3.4. uxadiazole-2-yl l benmute Thc drcnch was. applied at uni unc ratc and no crnpa en: Included In thc tc-l Table l (Part8) The percent weed control and percent of crop mjur} resulting imm a soil drcneh with certain OXl/ules and oxadia/olex Percent (ontrol Percent IHJUH phen l ll ,flA-oxudiumlc- Z-yll hen/mite Table l-(ontinucd (Part B} The percent weed control and percent ot'crop llljuf} resulting from a soil drench ith certain ouuoles and osudialolcs Percent Control 'l he drench as applied .it onl um: talc and no crops were included In the test '1 it figure based on onl\ pigueed EXAMPLE 36 This procedure shows that the oxazolcs and osadialoles are effective preemergence herbicides when applied to the soil surface as a surface spray.

To prepare an emulsion for spraying 2456 g otchemplanted with one of the following species: Rough pig weed. purslane common morningglory [Ipomoeu purpurcu (L.) Roth]. large crabgrass. barnyardgrass and either quackgrass [Agropyrun repens (L) Beauv.] or giant foxtail. The weed seeds are then covered with a thin layer of soil. After spraying. the soil in each pot is ical may be dissolved in 24 ml henzene optionally with 35 3; of a conventional surfactant such as polyoxyethyll-m d fi capacny by Sublrngmmn After cne sorhitan monooleatc (condensation product ofeth- [he z l the are wamred from ylene oxide [Ill molesl with sorhitan monoolcate). above wnh a The final \olume may be adjusted to 80 ml with dis- The percent weed control and crop injury are retilled water. Further dilutions of'ltl and 10 ml aliquots 3U corded l4 days after treatment. The results are re to 40 ml may he made with distilled water The soluported in Table ll The conditions of this test are more tions are sprayed with a pendulum sprayer delivering closely related to the manner in which these chemicals 3(I gals/A. making applications ol 8. 4 and 2 lhs/A with would he used in the field The results indicate that the the respective solutions. Two seeds olcorn. cotton and oxazoles and oxadiazoles are effective herbicides for soybeans were planted in greenhouse soil in 6-inch 35 the control of hroadlcaf and grass weed species, and plastic pots as described in Example 35. The soil surthat these compounds can selectively control weeds face is then partitioned into six parts. Each part is without severely injuring certain crops.

Table II.

The percent weed control and percent of crop injury resulting from a surface spray with certain oxa/oles and oxadiayoles Percent Control Table ll. (ontinued The percent weed control and percent of crop injury resulting from a surface spray with certain oxa/oles and oxadlaloles Percent Control Broadleaf (Brass Common Barn- (iiant v In ury Rate Pig Purs- Morningyard (rah Quacltl-ox- (ob Soy- Compound lB/A weed lane glory grass grass grass tail ('orn ton beans ()elyl 2-t5- he|i l-l 3.4- 3 so u 5a 7a So u (I o osadia/ole-Z-yl) bcn/oate 4 X 50 70 K0 b0 0 0 0 K Ill K5 K5 70 ll 40 ll Dodecyl 2-(5-phenyl-l.1.-l- 2 (ill ll") 10 Ill ll (I 41) ll oxudia/oleQ-yll l cn/oatc 4 80 50 50 50 It) (I 40 ll 8 K5 5U 5U 5U 5H 0 -lll ll 'Purslallc could not be c\.|luatc\l in this tc l because ol damping nl l EXAMPLE 37 This procedure shows that the oxidiazoles are effective against purple nutsedgc t(' vperu.v rulundm L.).

The chemicals are prepared for treatment by mixing 0.0[8 g chemical with 50 g tine sand. using a mortar and pestle. The sand and chemical are then transferred to a wide-mouth jar and blended for IS minutes in a rotary seed mixer. The sand and chemical mixture is then mixed with 400 g greenhouse soil by tumbling in a soil mixer. The soil is then equally divided between three 2.5 inch pots. One purple nutsedge nutlet is planted one inch deep in each pot. The pots are subirrigated. The percent control is determined l4 days after emergence. The results are reported in Table lll.

Table III The percent control of purple nulsedge resulting front the soil incorporation of certain oxadia/oles Percent Control Awnige of Three (ompound Replications hen/oic acid EXAMPLE 38 This example will further substantiate the effectiveness of the oxadiazoles in controlling members of the The major weed in the bog was nutgrass t('ypvm.v tit-mums Torr.l. a member of the Cyperaceae family. At all three rates weed control was I00? and there was no crop injury. This activity of the oxadiazoles is particularly unique in that it results in the control of a weed which is difficult to control in a crop on which few her bicides can be used.

EXAMPLE 39 This example will show that certain oxaioles and oxa diazoles are also active as postemergence herbicides.

A 6000 ppm sodium salt solution of the chemical to be sprayed may be prepared by dissolving 0.6 g of the chemical and a stoichiometric amount of 5'.) sodium bicarbonate in It] ml acetone (and optionally 30 mg isooctylphenylpolyethoxyethanol) and then diluting to l l00 ml. One purple nutsedge nutlet is planted in the center of a 4.5 inch pot. The following weeds are planted as described in Example purslane. rough pigweed. common morningglory. large crabgrass. barnyardgrass. and giant foxtail. The plants are maintained in a l6 hour photoperiod. The plants are sprayed when the broadleaf weeds are 1.5 inches tall and the grass weeds are l to 3 inches tall. The plants are sprayed to runoff with a De \'ilbiss No. I52 sprayer from a distance of 18 inches for 20 seconds at 20 psi. There are two replications. The pots are subirrigated. 'l he percent weed control is determined five days after treatment. The results are reported in Table l\.

The results indicate that the oxazoles and oxadiazoles are effective in controlling weeds when applied as a postemergence herbicide.

Table IV The percent weed control resulting from u puxtemergencu apran with certain UXLl/Hlch and uxndiu/ulca at 6000 ppm Percent Weed Control EXAMPLE 4U Emmplc 35 is rcpcatcd. using chemicals as shown in Table V. with thc results listed in said Table.

Table V.

The percent weed control frum a soil drench with certain oxu/nlcs and oxudiumles Percent Weed Control C ummon Burn- Having thus described our invention. what we claim and desire to protect by Letters Patent is:

l. A chemical having the structural formula wherein R is selected from the group Consisting of phenyl. phenyl substituted with up to three suhstitutents wherein the suhstitutents are halo. nitro. alk \l hav ing up to 4 carbon atoms or alkoxy having up to 4 carbon atoms. 4-meth \'l-2-( pyridyl I-5-thiazol \'l. 5 alkyl having up to 6 carbon atoms. and 3-p \rid \l;

and R is hydrogen, alkali metal. ammonium. or a moiety having up to 12 carbon atoms selected from alkyl. alkynyl and epox \alk 2. A chemical as in claim I in which R is phen5l. 3. A chemical as in claim I in which R' is hydrogen 4. A chemical as in claim I in which R is alkyl. 5. The chemical of claim 1 in which R is phenyl and R is hydrogen.

6. The chemical of claim 1 in which R is phen and 15 R is n-hutyl. 

1. ACHEMICAL HAVING THE STRUCTURAL FORMULA 2-(2-(R''-OOC-)PHENYL),5-R-1,3,4-OXADIAZOLE WHEREIN R IS SELECTED FROM THE GROUP CONSISTING OF PHENYL, PHENYL SUBSTITUTED WITH UP TO THREE SUBSTITUTENTS WHEREIN THE SUBSTITUTENTS ARE HALO, NITRO, ALKYL HAVING UP TO 4 CARBON ATOMS OR ALKOXY HAVING UP TO 4 CARBON ATOMS 4-MRTHYL-2-(PYRIDYL)-5-THIAZOLYL, ALJYL HAVING UP TO 6 CARBON ATOMS, AND 3-PYRIDYL; AND R'' IS HYDROGEN, ALKALI METAL, AMMONIUM, OR A MOIETY HAVING UP TO 12 CARBON ATOMS SELECTED FROM ALKYL, ALKYNYL AND EPOXYALKYL.
 2. A chemical as in claim 1 in which R is phenyl.
 3. A chemical as in claim 1 in which R'' is hydrogen.
 4. A chemical as in claim 1 in which R'' is alkyl.
 5. The chemical of claIm 1 in which R is phenyl and R'' is hydrogen.
 6. The chemical of claim 1 in which R is phenyl and R'' is n-butyl. 